The US's top aviation safety investigator is to hold hearings on the safety of lithium-ion batteries similar to those used in Boeing's now grounded 787 Dreamliner jets.

The hearings are likely to put more pressure on Boeing as it fights to get its jets back in the air. Transport secretary Ray LaHood has said plans to fix its battery issues will face "a lot of questions".

On Thursday, the National Transportation Safety Board (NTSB) released its interim report into the fire that broke out in the battery of a 787 parked at Boston's Logan airport in January.

Releasing the findings, Deborah Hersman, the NTSB chairman, said she planned to hold a meeting next month to explore lithium-ion battery technology and transport safety. It would help the industry "better understand the risks and benefits associated with lithium batteries, and illuminate how manufacturers and regulators evaluate the safety of new technology," Hersman said.

She has already criticised the certification process for the battery. "The expectation in aviation is to never experience a fire aboard an aircraft," she said in January.

Robert Mann, founder of consultant RW Mann, said: "It's pretty tough to come up with a solution if you haven't found the cause." He said the investigation could now widen beyond the battery.

Mann said that the cargo industry had serious concerns about lithium-ion technology and was likely to raise those concerns at the NTSB meeting. A fatal fire broke out on UPS flight in Dubai in 2008 that had been carrying large quantities of lithium ion batteries.

Lithium-ion batteries have caused fires in cars, computers and mobile phones as well as small aircraft. The Dreamliner is the first large passenger jet to use the lightweight technology on such a scale. As well as the Boston fire, a battery in an All Nippon Airways 787 set off a smoke alarm while in flight, triggering an emergency landing. That incident is now being investigated by Japanese authorities.

The delays to 787 deliveries led Boeing rival Airbus to ditch plans to use lithium-ion batteries on its wide-body jet, the A350-XWB.The 499-page report is the most detailed yet into what went wrong. The NTSB report makes clear it has yet to find a root cause for the fire. The board is still early in the investigation into the cause of the blaze on the Boston battery and experts said investigators may never determine a root cause because the battery was so badly burned.

"With the grounding of the 787 fleet, concurrent international incident investigations, redesign and re-certification activities taking place simultaneously, it is essential to provide the aviation community, policy makers and the public with the factual information we are developing," said Hersman. "Releasing an interim report provides a window into the significant investigative work that has been accomplished so far."

Boeing had delivered just 50 of its Dreamliner jets when the issue emerged and faces penalties if future deliveries are not made on time. It delivered a plan to address the battery issues to the Federal Aviation Administration (FAA) on 22 February.

That plan is believed to involve a stronger casing for the batteries, reinforced separation between its eight cells and a venting system that would direct potentially hazardous gases outside the jet.

LaHood told the Wall Street Journal that Boeing's plans would come under intense scrutiny. "I have made it very clear that I want a thorough review" of the Boeing plan, LaHood said. "I am going to ask a lot of questions" before a final decision is made.